Differentiating internal and external rotation of the upper arm
For external rotation you can focus on moving the front of the arms (the biceps side) outwards. For internal rotation you can focus on moving the biceps inwards. Note that the point of the elbow follows the rotation of the upper arm and so you can also use the point of the elbow as a reference for upper arm rotation relative to the shoulder.
Getting a feel for forearm rotation
Note that the forearms can rotate relative to the upper arms and so it is important to be able to distinguish between upper arm rotation relative to the shoulder and forearm rotation relative to the upper arm.
To get a feel for forearm rotation, practice rotating the forearms with the elbows bent, while keeping the upper arms still. Starting with the palms facing down, external forearm rotation will turn the palms inwards and then upwards. From here, internal forearm rotation will turn the palms inwards, and then downwards, and then if rotation is continue, outwards.
Muscles that Stabilize (and move) the Scapula
Prior to rotating the upper arms relative to the shoulder blades it can help to position and then stabilize the shoulder blade of each arm.
Muscles that attach the shoulder blade (or scapula) to the ribcage include:
- serratus anterior,
- rhomboid major and minor,
- levator scapulae and
- pectoralis minor.
These muscles can be used to move the scapulae relative to the ribcage. They can also be used to stabilize it or fix it in place relative to the ribcage. Read more about using these muscles in scapular awareness.
Muscles that Act on the Shoulder Joint
Muscles that attach between the shoulder blade and the humerus include:
- subscapularis (which is located on the front surface of the shoulder blade, between it and the ribcage)
- supraspinatus (located along the top of each scapulae, above the "spine" of the scapulae.)
- infraspinatus, (located on the back of each scapulae below the spine of the scapulae),
- teres minor, (located just below infraspinatus) and
- teres major (located below teres minor.)
The first four of these muscles constitute the rotator cuff. Their tendons attach high up on the humerus close to the "ball" of the shoulder joint.
The teres major, with its tendon inserting further down the arm bone isn't included in this group even though it shares a similar name.
Other muscles that attach the scapulae to the arm bones include
- the deltoid,
- triceps long head.
The triceps long head and the biceps both attach to the bones of the forearm (the radius and ulna.)
Of all the muscles that cross the shoulder and attach the scapula to the humerus, the muscles of the rotator cuff are closest to the shoulder joint itself.
Rotator Cuff Individual Muscle Function
The supscapularis attaches to the front of the humerus. When it contracts it rotates the humerus internally (causing the front of the upper arm bone to roll inwards.)
The infraspinatus and teres minor both attach to the back of the upper arm bone. When contracted they rotate the upper arm bone externally.
The supraspinatus attaches to the side of the upper arm bone near the top. When contracted it abducts the arm pulling it out to the side.
When all of these muscles are contracted together so that the work against each other the feeling can be like you are tightening or squeezing the shoulder joint. You could also think of this action as "pulling" the arm into the shoulder socket.
Neck Posture for Shoulder Rotation Exercises
For all of these exercises work at keeping your neck long.
Depending on whether you are doing external shoulder rotation or internal you may find it helps to either lift your chest (bend your thoracic spine backwards) or drop your chest (bend your thoracic spine forwards.) In either case work at making your neck feel long.
So that your neck and shoulders work together you may find that these shoulder exercises are more comfortable if you move your neck chest and shoulders in sync. To begin with practice just the chest (and neck) movements in isolation. Then add the shoulder rotations to that movement.
Start by lifting your ribcage and then lowering it. As you lift your ribcage lengthen your neck. As you lower your ribcage relax your neck and leg your head move forwards.
Repeat slowly and smoothly.
You may find that you automatically inhale when lifting your chest and automatically exhale while lowering it.
External Shoulder Rotations with Arms Down
Start with your arms relaxed and down by your sides. Start by lifting and lowering your chest. Then as you lift your chest rotate your arms outwards. As you relax your chest let your arms relax and return to "neutral."
Notice how, in the pictures above, externally rotating the shoulders "opens" the fronts of the shoulders. If you look at the pictures below you can see that externally rotating the arms "closes" the back of the upper body, or contracts it.
In this instance my shoulder blades are squeezed together. If you work at maximizing external rotation, you may find that your shoulder blades naturally tend to draw together.
An optional approach is to retract your shoulder blades first. Then externally rotate the arms. Then relax and then repeat. In this case, make sure that you make the first two steps distinct. First retraction, then external rotation.
Internal Shoulder Rotation with Arms Down
Next practice internal rotation with the arms down.
Initially focus on your arms and shoulders. Rotate the arms inwards, notice how if you maximize the movement your shoulder blades protract. Then relax and repeat.
Notice how in the picture above, the front of my shoulders look more "closed" while internally rotated. In the picture below you can see how my shoulder blades have protracted or spread apart.
Once you are comfortable with feeling your arms and shoulder blades, again try leading with the shoulder blades. First protract, then rotate your arms inwards. Relax and repeat.
If you want to add your chest, actively pull your chest down and exhale. While exhaling, protract your shoulder blades and then rotate your arms inwards. Relax all actions as you inhale.
Arms Down by Sides with Elbows Bent
Rotating your upper arms with elbows bent upwards as show (upper arms down by your sides) can be tricky. So that you whether or not you are rotating your upper arms, for this exercise first rotate your forearms, then rotate your upper arms (while keeping the forearms rotated).
For external rotation, first rotate your forearms externally. Then rotate your upper arms. Then relax and repeat.
Once you have a feel for it, add shoulder blade retraction.
Externally Rotated with shoulder blades retracted
Repeating the same process for internal rotation, first rotate your forearms internally. Then rotate your upper arms. Relax and repeat. Then add shoulder blade protraction.
Internally Rotated with shoulder blades protracted
Arms Out to Sides
With arms out to the sides, you can practice rotating first your upper arms and then your forearms.
For both internal and external rotation, you can work at keeping your shoulder blades spread apart. However, do notice, when externally rotating your arms, your shoulder blades should descend. When internally rotating, your shoulder blades should lift.
Arms To Side Elbows Bent
Here again you may find it easier if you rotate your forearms first, then your upper arms. As with arms straight out to the sides, notice your shoulder blades descending with external rotation of the upper arm and descending with internal rotation of the upper arms.
Arms Forward Elbows Bent
Here again with elbows bent you may find it less confusing if you rotte your forearms first and then your upper arms.
In these two pictures you may find it more helpful to look at my armpits. The first picture is actually neutral, the second is with my upper arms externally rotated. My biceps are moving "outwards".
Note that internally rotating the arms with the arms up is difficult. However, if you reach the outer edge of your shoulder blade up you may find that you have room to do the internal rotation with your arms in this position. If you feel or get a sense of bone grinding against bone then don't do the internal rotation with arms up exercise.
The rotator cuff exercises above are relatively simple. However while doing them focus on "working" while inhale and then relaxing while exhaling.
While doing the active phase of each exercise, make the arms feel long and the shoulders open so that you add tension to the connective tissue trains of your arms. In addition lengthen your spine (particularly your neck) and expand your ribcage.
When doing the active phase and relaxing phase of each exercise focus on moving smoothly between each extreme. Feel your body as you do this.
For more shoulder exercises check out the dance of shiva.